We got Bailey at 3 months, she and her 14 brothers and sisters all slept in a large crate (Mom had her own large crate...with 15 pups she needed a break.) When we brought her home, we also brought a large crate. Bailey slept in her crate every night for 2 months, but was uncrated when we were home (and I was home for two months.) I started leaving her out of her crate with me away for 15 minutes, 20 min, 30 min, etc., Every time I came in, I would refrain from acknowledging her until I had checked the house, once everything was A-OK, love and treats were lavished upon her. As she grew up, she grew out of her need for a crate and rarely went near it, eventually we took it down and donated it. It was a great tool, and she benefited from it, but it was never a place of fear and abuse.
I have always made my feelings about crate abuse known: if you have to lock your dog up all day, all night, it's abuse, it's inhumane. Quality of life is as important as life itself. Imagine yourself in solitary confinement, with one hour a day in the exercise yard. It would be an existence, but it wouldn't be a quality life. I wouldn't do that to someone I loved.
By the way, Bailey is a calm, patient, curious, loving, outgoing dog who settles at the vets without fuss, even when it requires being crated. A life of enrichment leaves her balanced and in control. Long days locked in a crate wouldn't have produced her calm nature.
I have much thanks to extend to the Mastiff Forum and it's members who were my best resource for negotiating the do's and don'ts of raising a well balanced dog, including REASONABLE guidelines for crate usage.